1. Field of the Invention
The present invention relates to a plant growth regulator, more specifically to the utilizing of an action thereof of lowering the content of endogenous ethylene in a plant, which comprises a substituted dicarboxylic acid derivative, as an active ingredient, having the formula [I]: ##STR2## wherein R.sup.1 and R.sup.2 are, same or different, a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a C.sub.1 -C.sub.3 alkyl group or together represent a C.sub.3 -C.sub.5 alkylene group or a divalent organic group represented by the formula, --CH.dbd.CH--CH.dbd.CH--, optionally substituted by X.sub.n to form a cyclic group; R.sub.3 is a hydrogen atom or a C.sub.1 -C.sub.3 alkyl group; R.sub.4 is a cyano group or a group represented by the formula, --COOR.sup.5, --CH.sub.2 COOR.sup.5 or --CONR.sup.6 R.sup.7 ; and D and G are a group represented by the formula, --COOR.sup.8 or --CONR.sup.9 R.sup.10, and N--H respectively with non-bonding, or are taken together to form CO--N, in which Xn is, same or different, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a C.sub.1 -C.sub.4 alkyl group, a C.sub.1 -C.sub.4 alkoxy group, a hydroxyl group, a nitro group or an amino group, and n is 0, 1, 2, 3 or 4, R.sup.5 is a hydrogen atom or a C.sub.1 -C.sub.6 alkyl group, R.sup.6 and R.sup.7 are, same or different, a hydrogen atom, a C.sub.1 -C.sub.4 alkyl group or together represent a C.sub.3 -C.sub.5 alkylene group optionally substituted by a methyl group, R.sup.8 is a hydrogen atom or a C.sub.1 -C.sub.6 alkyl group, R.sup.9 and R.sup.10 are, same or different, a hydrogen atom, a C.sub.1 -C.sub.4 alkyl group or together represent a C.sub.3 -C.sub.5 alkylene group optionally substituted by a methyl group, and physiologically acceptable salts thereof, and an inert carrier or diluent.
2. Description of the Related Art
It is known that ethylene formed in a plant body promotes the aging of the plant, and if this aging can be inhibited, various possibilities arise; for example, an extension of the life of cut flowers and potted flowers, a prevention of the falling of the flowers and fruit of vegetables and fruit trees, and a regulation of the period of the maturity and an increase of the yield of fruit.
Accordingly, there is a strong demand for the development of a compound capable of lowering the content of endogenous ethylene in a plant and which can be utilized as a plant growth regulator.
As a result of intensive studies into solutions to the above problems, the present inventors found that a substituted dicarboxylic acid derivative having the formula [I] can be used as an active ingredient of a plant growth regulator, and thus accomplished the present invention.